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Volunteered Geographic Information and OpenStreetMap

Short introduction to the subject of Volunteered Geographic Information and outlining some of the characteristics, issues themes of VGI
and then a comprehensive talk about the OpenStreetMap Project.
By Tim Waters, at AGI Northern Group (SIG), April 2009, Manchester University

4.
VGI
Volunteered Geographic Information (VGI) is the harnessing of tools to create,
assemble, and disseminate geographic data provided voluntarily by individuals
(Goodchild, 2007).
Some examples of this phenomenon are Wikimapia, OpenStreetMap,
and Google MyMaps.
These sites provide general base map information and allow users to create their own content
by marking locations where various events occurred or certain features exist,
but aren’t already shown on the base map.
VGI is a special case of the larger Web phenomenon known as user-generated content.
Straight outa Wikipedia.............there's more pictures later.

5.
Power of Volunteered Geographic Information
1. Potential of VGI to expand/complete/improve existing databases,
infrastructures, & archives;
2. Potential of VGI to enable us to gather/produce new forms of
spatial information that use local knowledge to inform previously un-
answerable questions, unknowable phenomenon, and new social and
political practices. (“new knowledge practices”)

6.
Concerns:
what drives people to do this, how accurate are the results,
will they threaten individual privacy, and how can they augment more conventional
sources
Basics:
Web2 – web search, Google, communities
technologies, GPS cameras, network, computers
Crowd sourcing
price, closed of NMAs (OS licences) Push factor
Openness
Easy
Amateur
---
Future with NMAs etc. Decline in world mapping. Remote sensing and VGI filling in the
gap.
Mapping economically determined. None in developing world. Expensive to keep up to
date.
AND Map2.0

27.
OSM in a nutshell
Most other maps are non-free
Vector data for custom maps is difficult to obtain
licences
Users can improve the map
Fast updates
Commercial maps have intentional errors
Many areas of the world are mapped poorly
Speciality maps
Innovative uses

97.
http://blog.fortiusone.com/2008/12/12/openstreetmap-vs-googleteleatlas-street-coverage/
OpenStreetMap vs. Google/TeleAtlas Street Coverage
The size of the circles are proportional to the values for both, so small circles equal poor coverage
and large circles equal good coverage.
The overlap of the circles shows who appears to be doing better
(orangey/brown showing means that osm is doing better, blue google). OSM is the top layer so a tie will have
OSM looking better, but you can click the layers on and off to see both views of the coverage.

98.
The data is very interesting. Quickly comparing the roads layers against OSM in Kenya show
good correspondence where there is Yahoo aerial imagery to trace against — if OSM had access to the same imagery,
I imagine we’d be pretty much equivalent country-wide. MapMaker is slightly more complete in central Nairobi; I put that down to Google
having full time employees in Nairobi who work on MapMaker
Green = OSM
Purple = Mapmaker

101.
Positional accuracy
Area Average
On each tile, 100

difference
points sample with (m)
evaluation of distance Barnet 6.77
between OSM and Highgate 8.33
Meridian 2 New Cross 6.04
South Norwood 3.17
Can see significant

differences: from Sutton 4.83
about 3m to over 8m Total 5.83
http://povesham.wordpress.com/2008/08/07/osm-quality-evaluation/
UCL Muki Haklay
http://www.ucl.ac.uk/~ucfamha/OSM%20data%20analysis%20070808_web.pdf

102.
The analysis shows that, where OSM was collected by several
users and benefited from some quality assurance, the quality
of the data is comparable and can be fit for many applications.
The positional accuracy is about 6 metres, which is expected
for the data collection methods that are used in OSM. The
comparison of motorways shows about 80% overlap between
OSM and OS .
The challenges are the many areas that are not covered –
currently, OSM has good coverage for only 25% of the land
area of England
12 Months ago...
http://povesham.wordpress.com/2008/08/07/osm-quality-evaluation/
UCL Muki Haklay
http://www.ucl.ac.uk/~ucfamha/OSM%20data%20analysis%20070808_web.pdf